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Copper Deposition and Wafer Cleaning

Cu⁺ Monitoring in Electrochemical Deposition

Optical measurements provide real-time monitoring of copper and acid concentrations in ECD applications.  One of the unique capabilities of our Optical Solutions' brand filter photometers is to be able to simultaneously measure Cu in the visible (VIS) spectral region and acid concentration in the near-infrared (NIR).

We have developed a highly compact system based upon our ClearView photometer, a Teflon^® flow cell for direct connection with Teflon^® or other tubing and bendable fiber optic cable. The system is shown below.














This system will provide you with 3 4-20 mA outputs for Cu and acid concentrations and a diagnostic signal in real-time.  It can also be operated remotely over an etherlink network with our VirtualView software. 

Typical precision for Cu is ± 1 g/l and ± 4 g/l for acid.

Wafer Cleaning

For monitoring of wafer cleaning, we can offer one of our photometers, a ClearView or ChemView, for a single sample point or possibly two sample points from one analyzer.  

Our Model 412L spectrophotometer is a good choice for 3 and 6 sample points or where multiple calibrations and protocols are required at a single sample point.

SC-1

The following graphs shows an evaluation of an actual ammonium hydroxide calibration from the spectrophtometer for SC-1 based upon ASTM D 6122, D6708 and E155.


The actual ammonium hydroxide value is plotted on the vertical axis and the value predicted from the NIR model is on the horizontal axis.

The standard error of prediction (SEP) is ± 0.1% in this range up to 5%.  

Precision for hydogen peroxide and water is ± 0.3 %.    

SC-2

A similar calibration for HCl in the presence of hydrogen peroxide and water from Model 412L data is shown below.
The standard error for HCl is ± 0.1%, and ±0.3% for water and peroxide.











Other measurements, with similar precision to those described above, include:

• HF in water
• TMAH (tetramethylammonium hydroxide)
• NMP  (n-methyl pyrrolidene)